DE2217351A1 - ELECTRIC POWERED LAWN MOWER - Google Patents

Description

Wolf-Geräte GmbH., 524 Betzdorf / Sieg, Gregor-Wolf-Straße

Electric motor-driven lawn mower

The invention relates to a lawn mower with an electric motor
for driving the cutting tools and the chassis and with a control device for setting the drive speed of the chassis.

In an older proposal, which does not belong to the state of the art, of a lawn mower designed as a cage mower or cylinder mower, the drive speed of the ground roller serving as the chassis is set in rotation by the motor-driven knife cage roller via a gearbox that has a freewheel and at least two gears at a constant engine speed to use the bottom roller
drive two speeds. In developing this
Lawnmower was believed to be the available energy at
constant speed of the motor and the mowing spindle can be used particularly sparingly and a favorable efficiency can be achieved. Such an energy-saving operation should have advantages in particular for battery-operated lawn mowers. Of the
The disadvantage of this lawn mower, however, is that they only
can be driven at two defined speeds on the ground, which in practice cannot be regarded as sufficient in difficult terrain, so that one was often forced to reduce the speed of the

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Reduce the mower or shut it down when you are at a Resistance or the end of the lawn to be cut. The effort for a mechanical gearbox with more than two Aisles is too expensive for the lawnmower to be operated in the house garden and operation would also prove to be too difficult. The same applies to continuously variable mechanical transmissions, which also have a relatively poor degree of efficiency which precludes their use from the outset, especially in battery-powered mowers.

The invention is based on the object of an electric motor operated lawn mower to increase the ease of use by setting and changing the driving speed can be carried out quickly and within wide limits.

According to the invention, this object is achieved in a lawnmower of the type mentioned in that the control device to adjust the drive speed of the chassis a stepless speed setting of the electric motor by engaging in the Causes the excitation circuit and / or the armature circuit.

The invention is based on the knowledge that electronic speed control devices for electric motors of all types have recently been developed, which, for example, by phase control or the like. enable lossless control. Lousy speed controls, in which a considerable part of the available energy is destroyed in ohmic resistors, are not suitable for household lawn mowers, even if they are operated from the mains. For battery-operated lawn mowers, such a loss regulation is not an option anyway. ^:

The invention makes it possible to adjust the driving speed of the lawnmower individually, taking into account the Operator and taking the terrain into account. Particularly

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However, the control according to the invention proves to be advantageous when starting and stopping, because the driving speed is constant can be increased or decreased, so that a slipping of the chassis on the ground neither when accelerating nor when Braking takes place and running into obstacles can easily be avoided.

According to a preferred embodiment of the invention is the respect Its speed controllable electric motor via a manually operated clutch with the cutting drive and the travel drive detachable. Depending on the design of the cutting tools and the chassis, there are also suitable fixed reduction gears intended. The ease of use is increased in particular that when the clutch is engaged, the drive with the can run at the lowest speed and that only after the clutch has been engaged, gradually increasing to a higher speed and vice versa.

In order to rule out incorrect operation as far as possible, according to a further embodiment of the invention, the arrangement is made in such a way that that a single control lever with continuous adjustment, the necessary circuits in the desired order causes: First, the motor is connected to voltage, which is switched via the control device in such a way that it operates with the lowest Speed rotates, when the lever is pushed further, the clutch is engaged and only then is the Lever increases the speed. In this way, you will see one Particularly easy to operate when starting and also when stopping. The operating lever can according to a preferred embodiment of Invention be attached as a twist grip on the handlebar of the lawn mower.

The invention is for electrically powered lawn mowers of all types Applicable / The invention proves to be particularly advantageous

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however, in the case of lawnmowers designed as cylinder mowers, in which both the mowing spindle and one forming the drive mechanism The bottom roller can be driven by an electric motor. In this type of lawnmower, the cutting tool, i.e. the mower spindle, runs with a speed far below the speed of the engine. It has been shown that in such reel mowers the speed change of the mowing spindle, which is caused by the speed setting of the Motor is conditioned for the purpose of changing the driving speed, has no adverse effect on the mowing process and at slow driving with slowly rotating mowing spindle the same good results can be achieved as with fast moving Mower and fast rotating mower spindle. So it does not need to be taken care that the mowing spindle with constant Speed revolves as it was previously considered necessary,

In such a cylinder mower is according to a preferred embodiment the invention made the arrangement such that the structurally combined with a transmission engine and the clutch within the hollow bottom roller are arranged. This results in a particularly compact structure and the drive parts are protected within this roller in a favorable manner.

When training as a battery lawn mower, the battery can expediently can also be built into this bottom roller, the arrangement being made so that the stationary parts within the roller stand still and the drive only acts on the roller shell. It is already known for battery-operated cylinder mowers to install the battery in the bottom roller, but here the drive motor was provided in the knife cage roller (DT-OS 2 026 416).

When using a wet battery, care must be taken to ensure that it comes to a standstill within the roller. If a dry battery Is used, this can, however, be mounted rotating within the roller. With a battery mower, the DC motor

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excited both by permanent magnets and by a field winding will. Here, the motor is expediently designed as a geared motor and assembled with a planetary gear. The drive goes from the motor or gearbox via a coupling to the drive roller or, if necessary, the drive wheels, with Expediently, a gear train is again interposed between the clutch and the roller or wheels.

The spindle drive is expediently carried out by the output shaft of the geared motor via a toothed belt, a slip clutch being expediently arranged on the spindle in order to at Blocking the spindle to protect the motor.

In a structural embodiment of the invention, a clutch disc is seated on the motor shaft or gear shaft and is connected to the shaft is rotatably connected. The second coupling play is loosely connected to the shaft with a pinion so that it cannot rotate and only continues to run Engage the clutch with. The motor speed is set via the armature winding in permanently excitable motors or via the field winding in shunt motors.

With the same structure, one can be designed for a battery motor Lawn mowers can also be used for mains operation using a 220 volt motor or a j80 volt motor. It is there advantageous if this 220 volt motor has the same speed and gearbox as the DC motor. The stepless one Speed regulation is much simpler in such an AC motor and can be done, for example, by a phase control or a block control is effected. In the case of battery operation, a conversion is first required. Even however, this does not represent insurmountable difficulties, because nowadays speed control devices or speed regulating devices are used both for direct current motors and for alternating current motors are available that work losslessly and yet

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are available relatively cheaply. These regulating or control devices per se are not the subject of the present invention and all available methods can be used for this purpose, which meet the relevant conditions.

Exemplary embodiments of the invention are described below with reference to the drawing. In the drawing show:

Fig. 1 is a perspective view of a partially broken away reel lawn mower designed according to the invention with a drive unit housed in the ground roller,

2 shows a sectional view of the ground roller of another embodiment of a cylinder lawn mower,

FIG. 3 is a partial view of the operating handle of the lawnmower according to FIG.

FIG. 4 is a side view of the operating handle according to FIG.

The lawnmower according to Fig.l has in a housing at the front a mowing spindle 10 and, at the rear of the housing, a ground roller 12 which effects the travel drive. Between the mowing spindle 10 and the bottom roller 12 is a grass catcher 14. A guide handle 16 is attached to the housing. The one designed as a hollow roller Bottom roller 12 encloses a frame 18 which is laterally suspended on hollow shaft stubs 20 and the battery 22, the motor 24 and the transmission 26 structurally integrated with it carries. The focus of these units is so that the frame 18 always remains in its position shown. The transmission 26 is a slip clutch 28 is connected downstream, the output side of which carries a spur gear 30 which is connected to a spur gear mounted in the frame 32 meshes, which in turn meshes with a ring gear 34, which is fixed on the inner surface of the roller 12. This is used to drive the bottom roller. The mower spindle is controlled by the The output side of the clutch 28 is driven via a toothed belt 36. The engagement and disengagement of the clutch 28 takes place via a

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Baudenzug 38, which runs inside the guide bracket .16 and is connected to a switch 40 in the handle. Next to it, is located In the handle there is a device switch 42 for switching the motor on and off and the connecting lines 44 are for this purpose through the hollow axis 20 and the bracket to the interior of the handle led to switch 42. A rotary handle 46 in the handle is connected to the engine speed control via a construction cable 48 (not in FIG shown) in connection.

In the embodiment according to FIG. 2, corresponding parts are provided with the same reference numerals. The lawnmower shown here ■ differs from the lawnmower shown in Fig.l in particular by the appropriate type of operation. In this embodiment, the coupling 28 has a coupling disk 52 which is firmly seated on the motor output shaft 50 and a coupling disk 54 which slides loosely on the shaft and which is firmly connected to the drive pinion 30. The engagement of the clutch 28 takes place via a clutch lever 58 rotatably mounted at 56 via a linkage actuated by the construction hoist 60. The Baudenzug engages a displaceably mounted rod 62, öeren end piece 64 actuates a motor switch 66. This switch 66 is switched off when the rod 62 has reached its left end position. When the rod 62 is shifted to the right (according to FIG. 2), the switch 66 is first closed and then the coupling lever 58 is pivoted clockwise about the pivot point 56 according to FIG 54 comes into engagement with the clutch disk 52 which is already rotating. Only then does a further driver 72 of the rod 62 meet an actuating element J§, which is the setting element of the speed control device, for example a potentiometer. This setting member 74 is pressed by the spring 76 into the left starting position in which the lowest speed is set. By moving the adjusting member 7 ^ through the driver

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72 to the right there is an increase in speed. As can be seen from FIGS. 3 and 4, this setting takes place by means of a single rotary handle 78 to which a pointer 80 running over a fixed scale 79 is attached. This rotary handle 78 allows all functions to be carried out in the desired order. First, starting from the rest position according to FIG. 4, the motor is switched on by turning the handle. If you turn the handle further, the clutch for the drive is engaged via the construction cable. This then runs at the lowest speed. If the handle is turned further, the engine speed increases and with it the drive speed of the bottom roller. As can be seen from FIGS. 3 and 4, the overall setting takes place with a twist grip adjustment of a total of about 180 °. The turning of the motor is of the handle immediately upon initial rotation, while the clutch is turned on at about 45 ° rotation and carried out the rotational speed control between ⁰ and 90 ° l8o.

The illustrated embodiments show a battery-operated Lawn mower, however, the invention is not limited to a battery operated lawn mower, but it could also be a Mains-powered motor are used, the supply cable being led through the hollow shaft to the outside.

Claims

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Claims (11)

Patent claims: 1. Lawn mower with an electric motor to drive the cutting tools and the chassis and with a control device for setting the drive speed of the chassis, characterized in that the control device has an infinitely variable speed setting of the electric motor (24) caused by intervention in the excitation circuit and / or the armature circuit. - 2. Lawn mower according to claim 1, characterized by ^, that the speed controllable electric motor via a manually disengageable clutch (28) with the Cutting tools and the drive can be coupled. 3. Lawn mower according to claims 1 and 2, characterized in that upon rotation of a single operating handle (78) initially the motor is engaged and the speed is then regulated from low to high or vice versa. 4. Lawn mower according to claim 3, characterized in that before engaging the clutch by the operating handle (78) the electric motor is inserted via a switch (16, 66). 5. Lawn mower according to claims 3 and 4, characterized in that that the operating handle is arranged as a rotary handle on the guide bracket (l6) is. 309844/0042 - ίο - · 6. Lawn mower designed as a cylinder mower according to claims 1 and 2, in which both the mowing spindle and the travel drive forming bottom roller can be driven by an electric motor, thereby marked, that the motor (24), which is structurally combined with a gear (26), and the coupling (28) are inside the hollow bottom roller (12) are arranged on a frame (18) which remains stationary by gravity within the roller. 7. Battery reel mower according to claim 6,
characterized in that the battery (22) is also arranged within the hollow roller (12). 8. cylinder mower according to claim 6,
characterized in that the output member (54) of the clutch is connected to an internal ring gear (j54) of the bottom roller (12) via a spur gear (j5O, j52). 9. cylinder lawn mower according to claim 6 and 8, characterized in that that the output shaft (50) of the gear motor (24,26) carries a pinion (51) which via a toothed belt (36) the Mowing spindle (10) drives. 10. cylinder mower according to claim 9,
characterized in that a slip clutch is provided between the toothed belt (36) and the mowing spindle (10). 11. Cylinder lawnmower according to claims 3 to 5 * characterized gekennzei chnet that one of a Baudenzug (60) advocable switching rod (62) acts with its end (64) on a motor switch (66) over 309844/004? ./. a driver (70) pivoted and a clutch lever (58) A setting of the setting member (745 of the speed control device) is effected via a driver (72). 309844/0042 «Β Blank page